Flat bed knitting machines for warp knitting of fabrics usually have a plurality of knitting needles mounted on a reciprocally movable needle bar which imparts reciprocating movement of the needles along their longitudinal axes. Individual base yarns may be wrapped around the needles by yarn guides in turn mounted on a main guide bar. The main guide bar swings or oscillates forward and backward relative to the needle bar and needles and shogs across the needle paths in reciprocal directions so that the guides move with a lapping motion to wrap each base yarn partially or completely around a needle in order that the needle may form open or closed yarn loops. In single needle bar machines, the guide bar may shog more than one needle width in order that warps formed by the loops may be interconnected to form a warp knit fabric.
One or more secondary guide bars may be provided to guide secondary yarns which may be laid into or knitted into loops formed by the base yarns and/or which may extend in weft directions to connect adjacent wales together formed by the base yarns. In such instances the knitting needles used have been latch-type needles and the secondary guide bars have been such to shog only and not to swing in order that the secondary yarn may be laid across a needle and to engage a latch.
Use of latch-type needles usually results in slower operating knitting speeds since the speed of movement of the needles in a reciprocating direction caused by movement of the needle bar is limited by inertia forces resulting from movement of the latch. Latch-type needles in addition are usually larger than other type needles, as for example beard-type needles, such that spacing between needles is greater. Also latch-type needles are usually more expensive than beard-type needles and more prone to misknit since a latch-type needle will not operate to form further yarn loops in the event a latch is allowed to knock over or close without receiving a yarn as there will then be no yarn available to open the latch during knitting of subsequent courses. Latch-type needles also have a limited operating life as compared to beard-type needles because of wear of the latch pivot.
Beard-type needles normally have not been available for use in flat bed knitting machines since the needles require use of a presser bar to close the needle beards and because flat bed machines lack the space and control mechanisms for moving a presser bar. This has been particularly true when one needle of a flat bed knitting machine is to engage two or more yarns, as for example, a base yarn forming warp extending loops and a secondary yarn extending in a weft direction joining adjacent loops.
Modified beard needles can however be used in flat bed-type knitting machines without use of a presser bar where the modified needle has a slot in the shank of the needle adjacent the tip of the beard and where the slot is inclined with respect to the longitudinal axis of the needle. In these instances yarn is laid across the needle to engage in the slot after which it passes under the beard tip into the hook of the needle. The beard tip is bent towards the slot so that a previously formed loop may slip over the beard as the needle is retracted towards a trick plate.
It is important when using modified beard needles without a presser bar that the swing movement of the base yarn be precise with respect to the needle in order that the yarn will be laid accurately into the slot. This is particularly so when two or more yarns are to be engaged by a single modified beard needle and where one of the yarns is to extend in a weft direction across one or more needles in order to connect adjacent warps made of a base yarn.
It is therefore an object of my invention to provide for a flat bed-type knitting machine which may utilize beard-type knitting needles to allow fast operation of the machine and at the same time provide means by which a secondary guide bar and a main guide bar may be precisely swung in unison and which at the same time will allow individual shogging movment between the two bars in order that a secondary yarn may extend across one or more needle paths and which at the same time may be laid into a slot of a needle.